Wireless activity trackers may do more than log how many steps you take. Doctors are turning to them to understand which factors help patients recover faster from surgery.

Researchers at the Mayo Clinic in Rochester, Minnesota equipped nearly 150 heart-surgery patients over age 50 with Fitbit activity trackers on their ankles on the first day of their recovery. Since surgery among older patients often leads to a loss of health and mobility, they wanted to see if certain levels of activity could predict the patients’ recovery time.

In their results, published in the Annals of Thoracic Surgery, they report that patients who took the most steps every day were significantly more likely to leave the hospital earlier than those who were less mobile. Those who walked around 818 steps by the second day after surgery spent less than five days in the hospital, while those who walked only 220 steps were hospitalized for more than six days.

Patients who walked more were also more likely to go home from the hospital instead of to a nursing facility. For example, on the second recovery day, those who walked less than 200 steps on average were more likely to be transferred to a facility versus patients who walked over an average of 600 steps were likely to be discharged to their own homes.

While it makes sense that patients who are more mobile tend to recover faster, the study is the first to document the utility of remote monitoring devices to assess surgical recovery. “Although it is obvious that patients who recover mobility sooner are likely to have better outcomes, it is critical in the face of changing demographics and financial rules that we measure functional measures of recovery for individuals and populations,” they write.

Since the study involved a small number of patients, the researchers could not conclude whether there was a threshold of activity that predicted faster recovery. But with more studies like these gathering data from other remove monitoring devices, it may be possible to determine how much activity, on average, might be required of patients in order to recovery quickly and safely. Such information could also help doctors to know which patients might require longer hospital stays and more intensive care following surgery.